Respective development of mobile communications and broadband wireless access technologies has resulted in mutual penetration of their services. In order to meet a requirement of broadband mobile communications and a challenge of mobile broadband communications, an LTE (Long Term Evolution) communications system is introduced into the mobile communication technologies.
Application of an OFDM (orthogonal frequency division multiplexing) technology in the LTE communications systems enables sub-channels to be orthogonal to each other, which well resolves a problem of intra-cell interference. However, because the LTE system has a higher requirement for spectrum utilization, a single-frequency networking manner is introduced to improve the spectrum utilization, but this leads to a problem of inter-cell interference. For example, if neighboring cells use a same spectrum resource in an overlapping area covered by the neighboring cells, serious ICI (inter-cell interference) occurs in the overlapping area. It can be seen that, in the LTE communications system, the inter-cell interference is main interference that affects system performance.
In order to reduce the inter-cell interference, power control is separately performed for cells to adjust their respective downlink transmit power. However, as distributed control is less comprehensive, optimization can be performed only on a portion-by-portion basis, and optimal performance of an entire network cannot be achieved, resulting in poor system performance.